Multi-bit high-density memory device and architecture and method of fabricating multi-bit high-density memory devices

ABSTRACT

A structure, memory devices using the structure, and methods of fabricating the structure. The structure includes: an array of nano-fins, each nano-fin comprising an elongated block of semiconductor material extending axially along a first direction, the nano-fins arranged in groups of at least two nano-fins each, wherein ends of nano-fins of each adjacent group of nano-fins are staggered with respect to each other on both a first and a second side of the array; wherein nano-fins of each group of nano-fins are electrically connected to a common contact that is specific to each group of nano-fins such that the common contacts comprise a first common contact on the first side of the array and a second common contact on the second side of the array; and wherein each group of nano-fins has at least two gates that electrically control the conductance of nano-fins of the each group of nano-fins.

FIELD OF THE INVENTION

The present invention relates to the field of semiconductor devices;more specifically, it relates to a multi-bit high-density memory deviceand architecture and methods of fabricating multi-bit high-densitymemory devices.

BACKGROUND OF THE INVENTION

In an effort to drastically increase the density of memory devices thatare fabricated with conventional semiconductor processes and arecompatible with conventional complimentary metal oxide silicon (CMOS)technology, efforts have been directed to devices that combine normalphotolithographic groundrule and sub-photolithographic groundruledimensions. However, there is a “pattern-mismatch” when normalphotolithographic groundrule and sub-photolithographic groundrulestructures are used in the same structure. “Pattern-mismatch” can causeyield loss and imperfect connections. Therefore, there is a need for aninterface device, memory device, memory device architecture and methodof fabricating memory devices that use normal photolithographicgroundrule and sub-photolithographic groundrule structures that avoidsthis type of “pattern-mismatch.”

SUMMARY OF THE INVENTION

A first aspect of the present invention is a structure, comprising: astructure, comprising: an array of nano-fins, each nano-fin comprisingan elongated block of semiconductor material extending axially along afirst direction, the nano-fins arranged in groups of at least twonano-fins each, wherein ends of nano-fins of each adjacent group ofnano-fins are staggered with respect to each other on both a first and asecond side of the array; wherein nano-fins of each group of nano-finsare electrically connected to a common contact that is specific to eachgroup of nano-fins such that the common contacts comprise a first commoncontact on the first side of the array and a second common contact onthe second side of the array; and wherein each group of nano-fins has atleast two gates that electrically control the conductance of nano-finsof the each group of nano-fins.

A second aspect of the present invention is the first aspect, furtherincluding: a channel region in each nano-fin between adjacent gates ofthe at least two gates; and a respective source region and a respectivedrain region in each nano-fin, the respective source and drain regionsseparated by a respective channel region.

A third aspect of the present invention is the first aspect, wherein foreach group of nano-fins, at least one gate of the at least two gates isa control gate adjacent to an outermost nano-fin of the each group ofnano-fins and at least one gate of the at least two gates is a floatinggate between adjacent nano-fins of the each group of nano-fins andwherein the control gate is tied to a voltage source and the at leastone floating gate is electrically floating.

A fourth aspect of the present invention is the first aspect, furtherincluding, for each group of nano-fins, a gate dielectric between eachnano-fin of and gates of the at least two gates associated with each thegroup of nano-fins.

A fifth aspect of the present invention is the first aspect, furtherincluding at least one memory element electrically connected to at leastone of the nano-fins of the array of nano-fins.

A sixth aspect of the present invention is the fifth aspect, wherein theat least one memory element is selected from the group consisting ofanti-fuses, DRAM cells, phase-change memory cells, solid-electrolytememory cells, ferro-electric memory cells, magneto-resistive randomaccess memory cells, oxide based resistive memory cells andorganic-based resistive memory cells.

A seventh aspect of the present invention is the first aspect, wherein apitch of the nano-fins of the array of nano-fins in a second directionperpendicular to the first direction is less than a smallest pitchlithographically definable by a photolithographic system used to defineeach the at least two gates.

An eighth aspect of the present invention is the first aspect, wherein awidth of the nano-fins of the array of nano-fins in a second directionperpendicular to the first direction is less than about 50 nm.

A ninth aspect of the present invention is the first aspect, wherein awidth, in a second direction, of gates of the first and second set ofgates located between adjacent nano-fins of a same group of nano-fins isless than about 50 nm and a width, in the second direction, of gates ofthe first and second sets of gates located between nano-fins of adjacentgroups of nano-fins is equal to or greater than about 180 nm, the seconddirection perpendicular to the first direction.

BRIEF DESCRIPTION OF DRAWINGS

The features of the invention are set forth in the appended claims. Theinvention itself, however, will be best understood by reference to thefollowing detailed description of an illustrative embodiment when readin conjunction with the accompanying drawings, wherein:

FIG. 1A is a top view and FIG. 1B is a cross-sectional view through line1B-1B of FIG. 1A of a general micro-to nano address block (MNAB)illustrating the principles of operation of the MNAB;

FIG. 2 is an isometric view of a portion of a general nano cross bararray (NCA) memory according to the embodiments of the presentinvention;

FIG. 3A is a schematic diagram illustrating relative positions ofcontrol gates of MNABs relative to nano-fins of a nano-scale arrayaccording to an embodiment of the present invention;

FIG. 3B is a schematic diagram illustrating relative positions controlgates of MNABs relative to nano-fins of a nano-scale array according toother embodiments of the present invention;

FIGS. 4A through 8A are isometric views and FIGS. 4B through 8B arecorresponding top views of an exemplary fabrication process for anano-fin array and corresponding MNABs according to the embodiments ofthe present invention;

FIG. 9 is a schematic layout of a MNAB according to embodiments of thepresent invention;

FIG. 10 is a schematic diagram of a wordline or bitline portion of anano-scale cross bar array (NCA) according to the embodiments of thepresent invention;

FIG. 11 is a schematic diagram of a memory device incorporating NCAsaccording to the embodiments of the present invention;

FIG. 12 is a schematic diagram of an exemplary memory array using aone-dimension NCA according to the embodiments of the present invention;

FIG. 13 is a schematic diagram of a first exemplary memory array using atwo-dimension NCA according to the embodiments of the present invention;and

FIG. 14 is a schematic diagram of a second exemplary memory array usinga two-dimension NCA according to the embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A is a top view and FIG. 1B is a cross-sectional view through line1B-1B of FIG. 1A of a micro-to-nano address block (MNAB) illustratingthe principles of operation of the MNAB. MNABs provide selection of theindividual nano-fins of a nano-fin array. In FIGS. 1A and 1B, a MNAB 100includes first and second polysilicon control gates 105A and 105B andsingle-crystal silicon nano-fins 110A, 110B, 110C and 110D. Nano-fins110A, 110B, 110C and 110D include respective channel regions 115A, 115B,115C and 115D and drain (or source) regions 120A, 120B, 120C and 120Dand a common source (or drain) region 125. Channel regions 115A and 115Bare separated by an electrically floating doped-polysilicon region 130A.Channel regions 115B and 115C are separated by an electrically floatingdoped-polysilicon region 130B. Channel regions 115C and 115D areseparated by an electrically floating doped-polysilicon region 130C.Nano-fins 110A, 110B, 110C and 110D and first and second gates 105A and105B are formed on a dielectric layer 137. A thin dielectric layer 135electrically isolates first and second gates 105A and 105B and nano-fins110A, 110B, 110C and 110D from each other. Dielectric layer 135 alsoacts a gate dielectric for MNAB 100.

The doping level of channel regions 115A, 115B, 115C and 115D isselected so they conduct drain-source currents at zero gate bias similarto a depletion-mode field effect transistor. The work functiondifference between the floating doped-polysilicon regions 130A, 130B and130C and channel regions 115A, 115B, 115C and 115D induces inversionlayers in the channel regions causing them to conduct at zero gate-bias.Applying voltages to control gates 105A and 105B causes selected channelregions 115A, 115B, 115C and 115D to deplete (since the potential onelectrically floating doped polysilicon regions are strongly coupled tothe potential on control gates 105A and 105B) and no longer conduct.While four nano-fins are illustrated in FIGS. 1A and 1B, the number ofnano-fins between control gates 105A and 105B may any number equal to orgreater than two. Channel regions 15A, 115B, 115C and 115D may beintrinsic or doped.

Each nano-fin 110A, 110B, 110C and 110D has a width W1 (in a widthwisedirection) and is spaced apart from any adjacent nano-fin by a distanceW4 where (W1+W4) has a value that is less than the smallest pitchlithographically definable by a given technology. Pitch is width of aline and the width of a space between the line and an adjacent line. Forexample, for 130 nm technology, the smallest features that can be imagedand still meet critical dimension (CD) variation, line edge roughness(LER) and misalignment (MA) tolerance specifications for 130 nmtechnology have a 260 mm pitch. For 90 nm technology, the smallestdimensions that can be imaged and still meet CD variation, line edgeroughness LER specifications and MA tolerance have a 180 nm pitch.Control gates 105A and 105B have a width W2. The distance betweencontrol gates 105A and 105B is W3. W2+W3 has a value that is equal to orgreater than the minimum pitch that can be defined using lithography fora given technology. All lengthwise dimensions (perpendicular to thewidthwise direction) also have values that are equal to or greater thanthe smallest dimension lithographically definable by the giventechnology. In one example W1 is less than about 50 nm. In one example,W1 is between about 10 nm and about 20 nm. The perpendicular distancebetween adjacent nano-fins is W4. In one example W4 has a value that isless than the smallest dimension lithographically definable by a giventechnology. In one example, W1=W4.

Line/space pairs (a line and the space between the line and an adjacentline) having a pitch less than the smallest lithographically definablepitch may be called nano-scale lines and spaces.

In the example that channel regions 115A, 115B, 115C and 115D are dopedN-type, Table I illustrates how different channel regions may beselectively depleted, allowing selection of any of the four nano-fins110A, 10B, 110C and 110D.

TABLE I Applied Control Gate Voltage versus Nano-Fin Channel RegionConduction Control Control Channel Channel Channel Channel Gate 105AGate 105B region region region region Voltage Voltage 115A 115B 115C115D   =0 Volts <<0 Volts Conducts Depleted Depleted Depleted   <0 Volts<<0 Volts Depleted Conducts Depleted Depleted <<0 Volts   <0 voltsDepleted Depleted Conducts Depleted <<0 Volts   =0 Volts DepletedDepleted Depleted Conducts >=0 Volts   <0 Volts Conducts ConductsConducts Depleted >=0 Volts <<0 Volts Conducts Conducts DepletedDepleted   <0 Volts >=0 Volts Depleted Conducts Conducts Conducts  <<Volts >=0 Volts Depleted Depleted Conducts Conducts

The exact values of voltages applied depends on a number of parametersincluding the doping levels of the channel regions of the nano-fins, thedoping levels of the polysilicon regions, the oxide thickness and thenumber and widths of the nano-fins.

FIG. 2 is an isometric view of a portion of a general nano cross bararray (NCA) memory according to the embodiments of the presentinvention. In FIG. 2, nano-fins 145 are positioned perpendicular togroups of electrically conductive lines 150 and separated by rectifyingor memory (data storage) elements 155. Groups of nano-fins 145 areconnected to MNABs 160 similarly to nano-fins 115A, 115B, 115C and 115Dof MNAB 100 of FIGS. 1A and 1B. In one example, electrically conductivewires 150 are conventional micro-scale wires. In one example,electrically conductive wires 150 are nano-fins, which are connected toadditional MNABs (not shown). Nano-fins 145 may be wordlines connectedto wordline decoders through MNABs and lines 150 may be bitlinesconnected to column selects and/or sense amplifiers, or nano-fins 145may be bitlines connected to column selects/sense amplifiers throughMNABs (the MNABs connected to bitline address decoders) and lines 150may be the wordlines. Examples of devices suitable for use as memoryelements 155 include, but are not limited to anti-fuses, DRAMcapacitors, phase-change memory cells, solid-electrolyte memory cells,ferro-electric memory cells, magneto-resistive random access memory(mram) cells, oxide based resistive memory cells and organic-basedresistive memory cells, while rectifying elements may include but arenot limited to p-n junctions, diodes, Schottky barrier diodes,metal-oxide field effect transistors (MOSFETs) including p-channel FETs(PFETs) and n-channel FETs (NFETs), bipolar junction transistors oralternately the memory element may itself have rectifying properties.

FIG. 3A is a schematic diagram illustrating relative positions ofcontrol gates of MNABs relative to nano-fins of a nano-scale arrayaccording to an embodiment of the present invention. In FIG. 3A, a MNABlayout 165 includes sets of nano-fins 170A, 170B, 170C and 170D andcontrol gates 175A, 175B, 175C and 175D of the MNABs. Only a portion ofMNAB layout 165 is illustrated in FIG. 3A. The polysilicon regionsbetween the individual nano-fins, the sources, drains and channels ofthe nano-fins are not illustrated for clarity. Control gates 175A and175B select nano-fins from nano-fin set 170B. Control gates 175C and175D select nano-fins from nano-fin set 170C.

Control gates 175A, 175B, 175C and 175D are shown in ideal alignment torespective sets of nano-fins 170A, 170B, 170C and 170D. However, becauseof CD variation, LER and MA tolerances, often more or less than thedesigned number of nano-fins will be overlaid by control gates or willlie between the control gates. In the present example, four nano-finsshould be overlaid by each control gate, but as few as three and as manyas five could be overlaid because of CD variation, LER and MAtolerances. For, example, with 10 nm wide nano-fins spaced 10 nm apart,an LER of 6 nm can cause an unwanted overlap of a control gate and anadjacent nano-fin. This problem is overcome in the layout of FIG. 3B.

FIG. 3B is a schematic diagram illustrating relative positions controlgates of MNABs relative to nano-fins of a nano-scale array according toother embodiments of the present invention. In FIG. 3B, an MNAB layout180 includes sets of nano-fins 185A, 185B, 185C, 185D and 185E andcontrol gates 190A, 190B, 190C, 190D and 190E of the MNABs. Only aportion of MNAB layout 180 is illustrated in FIG. 3B. The polysiliconregions between the individual nano-fins of the same set of nano-fins(the floating gates), the sources, drains and channels of the nano-finsare not illustrated for clarity. Each of sets of nano-fins 185A, 185B,185C, 185D and 185E may have the same length L1 but every other set ofnano-fins is offset lengthwise by a distance L2. In other words, theends of nano-fins in alternating sets of nano-fins are staggered withrespect to each other on a first side of the array and on a second andopposite side of the array. The width of control gates 190A, 190B, 190C,190D and 190E is W2 described supra.

In FIG. 3B, nano-fin sets 185B and 185D are offset from nano-fin sets185A, 185C and 185E. Control gates 190A, 190B, 190C, 190D and 190E arealigned in the spaces created by the periodic offset of nano-fin sets185A, 185B, 185C, 185D and 185E. While each nano-fin set is illustratedas having four nano-fins, each set may have two or more nano-fins. Whilethe number of nano-fins in each set of nano fins need not be the samenumber, it is advantageous that the number of nano-fins in each set ofnano fins be the same number.

Control gates 190A and 190B select nano-fins from nano-fin set 185B.Control gates 190B and 190C select nano-fins from nano-fin set 185D.Control gates 190D and 190E select nano-fins from nano-fin set 185C.

Control gates 190A, 190B, 190C, 190D and 190E are shown in idealalignment to respective sets of nano-fins 185A, 185B, 185C, 185D and185E. In the layout of FIG. 3B, normal CD variation, LER and MAtolerances, will not cause more or less than the designed number ofnano-fins will be overlaid by (or lie between the) control gates. For,example, with 10 nm wide nano-fins spaced 10 with a CD of +/−2 nm, thewidth of four adjacent nano-fins would be 78 to 80 nm. This allows thestructure to “absorb” any CD, LER and misalignment related fluctuationsat the nanoscale or the lithographically defined gates.

In FIG. 3B, gates 190A, 190B and 190C do not extend past the ends ofnano-fin sets 185B and 185D (though they may), and gates 190D and 190Edo not extend past the ends of sets of nano-fins 185A, 185C and 185E(though they may).

FIGS. 4A through 8A are isometric views and FIGS. 4B through 8B arecorresponding top views of an exemplary fabrication process for anano-fin array and corresponding MNABs according to the embodiments ofthe present invention. In FIGS. 4A and 4B, a silicon-on-insulator (SOI)substrate 195 includes a buried oxide layer (BOX) 200 formed betweenlower and upper single crystal silicon layers 205 and 210. In oneexample, upper silicon layer is doped N or P type (depending on whetherthe MNAB will comprise PFETs or NFETs respectively) to a concentrationof between about 2E14 atm/cm³ and about 1E19 atm/cm³. Formed on a top ofupper silicon layer 210 is a dielectric hardmask layer 215. In oneexample, hardmask layer 215 comprises silicon dioxide. Formed on top ofhardmask layer 215 is a nano-imprint resist pattern 220 comprising setsof nano-fin images 225A, 225B, 225C, 225D, and 225E. While fournano-fins are illustrated in each set of nano-fin images 225A, 225B,225C, 225D, and 225E, the number of nano-fins in each set may be anynumber equal to or greater than two. Advantageously, each set ofnano-fin images 225A, 225B, 225C, 225D, and 225E should have the samenumber of nano-fins to reduce the number of different control gatevoltages that need to be generated and routed. Nano-imprint pattern 220is advantageously formed by a nano-imprint process. In a nano-imprintprocess, a polymerizable material is deformed by pressing a mold ortemplate into a layer of the photoactive material and then curing thematerial with UV light or heat while the mold or template is still inplace. After removal of the mold or template, a patterned layer of thenow polymerized material is left which has a negative topology withrespect to that of the mold or template. The nano-fin mold may be madeusing electron beam lithography, interferometric lithography or byself-assembly block copolymers. In self-assembly, periodic patterns areformed as a result of separation of the mixture into distinct phasesupon annealing. Alternately, instead of nanoimprint lithography,self-assembly or direct-e-beam write technologies could be used todefine the nano-fin structures.

In FIGS. 5A and 5B, nano-imprint pattern 220 (see FIGS. 4A and 4B) hasbeen transferred into hardmask layer 215 using the nano-imprint patternas an etch mask, the nano-imprint pattern is removed and the pattern inthe hardmask layer is transferred into upper silicon layer 210 (seeFIGS. 4A and 4B) by an etch process (for example—a reactive ion etch orRIE) selective to etch silicon over silicon dioxide to form sets of hardmask layer covered nano-fins 230A, 230B, 230C, 230D and 230E. Then asacrificial oxide is grown on all exposed surfaces of the nano-fins, thesacrificial oxide is removed (to remove damage to the silicon crystalstructure at the exposed surfaces of the nano-fins) and a gatedielectric layer (not shown in FIGS. 5A and 5B) is formed on all exposedsurfaces of nano-fins.

In one example, the gate dielectric layer is silicon dioxide (SiO₂),silicon nitride (Si₃N₄), silicon carbide (SiC), silicon oxy nitride(SiON), silicon oxy carbide (SiOC), organosilicate glass (SiCOH),plasma-enhanced silicon nitride (PSiN_(x)) or NBLok (SiC(N,H)). In oneexample, the gate dielectric layer is a high K (dielectric constant)material, examples of which include but are not limited metal oxidessuch as Ta₂O₅, BaTiO₃, HfO₂, ZrO₂, Al₂O₃, or metal silicates such asHfSi_(x)O_(y) or HfSi_(x)O_(y)N_(z) or combinations of layers thereof. Ahigh K dielectric material has a relative permittivity above about 7.

In FIGS. 6A and 6B, a polysilicon layer 235 is deposited on top of BOXlayer 200 and sets of hard mask layer covered nano-fins 230A, 230B,230C, 230D and 230E, and a chemical-mechanical-polish (CMP) is performedto coplanarize top surfaces 240 of hardmask layer 215 and a top surface245 of polysilicon layer 235. In one example, polysilicon layer 235 isdoped N or P type (depending on whether the MNAB will comprise PFETs orNFETs respectively) to a concentration of between about 2E16 atm/cm³ andabout 5E21 atm/cm³.

In FIGS. 7A and 7B, polysilicon layer 235 (see FIG. 6A) is masked andetched using an RIE selective to etch polysilicon relative to dielectriclayers to form control gates 250 of MNAB devices, as well as polysiliconregions 255 between individual nano-fins 260 of sets of nano-fins 230A,230B, 230C, 230D and 230E. Then, with the photo mask still in place, anRIE selective to etch silicon dioxide relative to silicon is performedto expose top surfaces 265 of nano-fins 260 not protected by polysiliconlayer 235. The distance L2 (described supra) is greater than the gatelength LG of control gates 250. LG is equal to or greater than thesmallest dimension lithographically definable by the photolithographicprocess used to define the control gates. L2 is greater than thesmallest dimension lithographically definable by the photolithographicprocess used to define the control gates. Next an extension ionimplantation of nano-fins 260 is performed. If the MNABs are to comprisePFETs, the extension ion implantation implants a P-type dopant species.If the MNABs are to comprise NFETs, the extension ion implantationimplants an N-type dopant species. The extension ion implant isoptional.

In FIGS. 8A and 8B, spacers 267 are formed on the sidewalls of controlgates 250 of MNAB devices. Spacers 267 are also formed on the sidewallsof polysilicon regions 255 between individual nano-fins 260 of sets ofnano-fins 230A, 230B, 230C, 230D and 230E. While shown extending fromthe top surface hardmask layer 215 to the top surface BOX layer 200,spacers 267 need only be thick enough over nano-fins 260 to prevent thesource/drain ion implant (described infra) from penetrating into theextension regions of the MNAB FETs. Thus, a source/drain offset isformed between the channel regions and the source/drain regions of theMNAB FETs described infra. This offset reduces gate tunneling near thesource and band-to-band tunneling near the drain.

While no spacers are illustrated in FIG. 8A on the sidewalls ofnano-fins 260, they may or may not be present depending on the thicknessof the conformal layer used to form the spacers, the dimensions of thenano-fins and the etch process used to form the spacers.

Next a source/drain ion implantation is performed into regions ofnano-fins 260 not protected by spacers 267 (or other, optionalprotection layers that may be formed over other regions of thenano-fins, for example, where memory cells are to be formed). If theMNABs are to comprise PFETs, the source/drain ion implantation implantsa P-type dopant species. If the MNABs are to comprise NFETs, thesource/drain ion implantation implants an N-type dopant species.

An optional metal silicide may be next formed over exposed surfaces ofsingle-crystal silicon and polysilicon.

FIG. 9 is a schematic layout of a MNAB according to embodiments of thepresent invention. In FIG. 9, a MNAB 270 includes four nano-fins 275A,275B, 275C and 275D, each including corresponding first source/drains280A, 280B, 280C and 280D, corresponding second source/drains 285A,285B, 285C and 285D, and corresponding channel regions 290A, 290B, 290Cand 290D.

Channel region 290A is positioned between a first control gate 295A anda first floating gate 295B and is electrically isolated from the firstcontrol gate by a gate dielectric layer 300A and from the first floatinggate by a gate dielectric layer 300B.

Channel region 290B is positioned between first floating gate 295B and asecond floating gate 295C and is electrically isolated from the firstfloating gate by a third gate dielectric layer 300C and from the secondfloating gate by a gate dielectric layer 300D.

Channel region 290C is positioned between second floating gate 295C anda third floating gate 295D and is electrically isolated from the secondfloating gate by gate dielectric layer 300F and from the third floatinggate by a gate dielectric layer 300F.

Channel region 290D is positioned between third floating gate 295C and asecond control gate 295E and is electrically isolated from the thirdfloating gate by gate dielectric layer 300G and from the second controlgate by a gate dielectric layer 300H.

A first contact 305A is provided to first control gate 295A and a secondcontact 305B is provided to second control gate 295E. A commonsource/drain contact 310 is provided to first source/drains 285A, 285B,285C and 285D.

FIG. 10 is a schematic diagram of a wordline or bitline portion of anano-scale cross bar array (NCA) according to the embodiments of thepresent invention. In FIG. 10, an NCA includes a nano-fin array 315which includes alternating and offset nano-fin sets 320A and nano-finsets 320B (arranged in the same pattern and spacing as nano-fin sets185A through 185E of FIG. 3B) and first and second MNABs 270A and 270B.On a first side of nano-fin array 315, first MNAB 270A is arrangedadjacent to first ends of nano-fin sets 320A and overlap nano-fins sets320B and on a second side of nano-fin array 315 second MNAB 270B isarranged adjacent to second ends of nano-fin sets 320B and overlapnano-fin sets 320A. MNABs 270A and 270B are similar to MNAB 270 of FIG.9 described supra. First ends of nano-fin sets 320B are contacted bysource/drain contacts 310A, and second ends of nano-fin sets 320A arecontacted by source/drain contacts 310B. Second ends of nano-fin sets320B are interdigitated by gate structures 325A (gate dielectric layers,control gates and floating gates as in FIG. 9) and first ends ofnano-fin sets 320A are interdigitated by gate structures 325B (gatedielectric layers, control gates and floating gates as in FIG. 9). Inother words, there is a region of gate 325B between each nano-fin ofeach set of nano-fin sets 320A and there is a region of gate 325Abetween each nano-fin of each set of nano-fin sets 320B. Each controlgate of gate structures 325A is provided with a gate contact 305A, andeach control gate of gate structures 325B is provided with a gatecontact 305B. First and second nano-fin sets are spaced a distance D1apart (where D1=W2 of FIG. 3B). It is advantageous for the number andspacing of nano-fins in every nano-fin set be the same number andspacing to reduce the number of different control gate voltagesrequired, though the sets of nano-fins may include different numbers ofnano-fins and/or different spacings of nano-fins.

FIG. 11 is a schematic diagram of a memory device incorporating NCAsaccording to the embodiments of the present invention. IN FIG. 11, amemory device 330 includes an array 335 of NCAs 340, bitline addressdecoders 345, sense amplifiers 350, wordline decoders and drivers 355and an MNAB voltage supply 360. Each structure 340 comprises an NCAillustrated in one of FIGS. 12, 13 and 14 and described infra. It isadvantageous for each NCA 340 to be identical in size and type, thoughthey may be different in size and type. The voltages (which in oneexample range between about −8 volts and about +8 volts) required by thecontrol gates to select the various nano-fins of each set of nano-finsin a nano-fin array are generally not the same voltages required by theconventional transistors of bitline address decoders 345, senseamplifiers 350, wordline decoders and drivers 355. Therefore, a separatecontrol gate power supply is required. The positions of wordline andbitline decoders and drivers, control gate voltage supplies and senseamplifiers may vary from those illustrated in FIG. 11.

When NCAs 340 are one dimensional (a single nano-fin array) and used forbitlines in conjunction with conventional (micro-scale) wordlines,bitline address blocks are coupled to MNAB voltage supply 360. When NCAs340 are one dimensional and used for wordlines in conjunction withconventional (micro-scale) bitlines, wordline decoders and drivers 355are coupled to MNAB voltage supply 360. When NCAs 340 are twodimensional and used for both wordlines and bitlines, wordline decodersand drivers 355 and bitline address decoders 345 are both coupled toMNAB voltage supply 360.

FIG. 12 is a schematic diagram of an exemplary memory array using aone-dimension NCA according to the embodiments of the present invention.In FIG. 12, an NCA 340A (which is an example of NCA 340 of FIG. 11)includes a nano-fin-array 315A (similar to nano-fin array 315 of FIG.10) and a conventional wire set 365 arranged perpendicular to nano-finarray 315A. Memory elements are located at the crossover points of thenano-fins of nano-fin array 315A and the wires of conventional wire set365, as illustrated in FIG. 2 and described supra. The positions ofcontrol gates are indicated in FIG. 12 by the notation “CG.”

FIG. 13 is a schematic diagram of a first exemplary memory array using atwo-dimension NCA according to the embodiments of the present invention.In FIG. 13, an NCA 340B (which is an example of NCA 340 of FIG. 11)includes a first nano-fin-array 315B (similar to nano-fin array 315 ofFIG. 10) and a second nano-fin-array 315C (similar to nano-fin array 315of FIG. 10) arranged perpendicular to first nano-fin array 315B. Memoryelements are located at the crossover points of the nano-fins of firstnano-fin array 315B and the nano-fins of second nano-fin array 315C asillustrated in FIG. 2 and described supra. The positions of controlgates of first nano-fin array 315B are indicated in FIG. 13 by thenotation “CGB” and the positions of control gates of second nano-finarray 315C are indicated in FIG. 13 by the notation “CGC.”

FIG. 14 is a schematic diagram of a second exemplary memory array usinga two-dimension NCA according to the embodiments of the presentinvention. In FIG. 14, an NCA 340C (which is an example of NCA 340 ofFIG. 11) includes a first nano-fin-array 315D (similar to nano-fin array315 of FIG. 10) and a second nano-fin-array 315E (similar to nano-finarray 315 of FIG. 10) arranged perpendicular to first nano-fin array315D. Memory elements are located at the crossover points of thenano-fins of first nano-fin array 315D and the nano-fins of secondnano-fin array 315E as illustrated in FIG. 2 and described supra. Thepositions of control gates of first nano-fin array 315D are indicated inFIG. 14 by the notation “CGD” and the positions of control gates ofsecond nano-fin array 315E are indicated in FIG. 13 by the notation“CGE.” The positions of source/drain contacts of first nano-fin array315D are indicated in FIG. 14 by the notation “SDCD” and the positionsof source/drain contacts of second nano-fin array 315E are indicated inFIG. 13 by the notation “SDCE.”

Each adjacent pair source/drain contacts SDCD of first nano-fin array315D are connected to a 2:1 multiplexer 375. Each adjacent pairsource/drain contacts SDCE of second nano-fin array 315E are connectedto a multiplexer 380. The multiplexers reduce the number of source/draincontacts along the periphery of NCA 340C by a factor of 2. Thisprinciple can be further extended by using M:1 multiplexers to reducethe number of source/drain contacts along the periphery of NCA 340C by afactor of 2^(M).

NCA 340A of FIG. 12 may be fabricated by:

-   (1) performing the steps illustrated in FIGS. 4A through 8A and 4B    through 8B and described to form a nano-fin array;-   (2) forming memory elements connected to points along each    nano-fins; and-   (3) forming conventional wires crossing over and perpendicular to    the nano-fin array and connected at corresponding points along the    conventional wires to corresponding memory elements.

NCA 340B of FIG. 13 or NCA 340C of FIG. 14 may be fabricated by:

-   1) Performing the steps illustrated in FIGS. 4A through 8A and 4B    through 8B a first time to form a first nano-fin array;-   (2) forming memory elements connected to points along each    nano-fins;-   (3) forming another semiconductor layer over the memory elements and    the first nano-fin array; and-   (4) performing the steps illustrated in FIGS. 4A through 8A and 4B    through 8B a second time to form a second nano-fin array crossing    over and perpendicular to the first nano-fin array and connected at    corresponding points along the nano-fins of the second nano-fin    array to corresponding memory elements.

Thus the embodiments of the present invention provide for a memoryinterface device, memory device, memory device architecture and methodof fabricating memory devices that use normal photolithographicgroundrule and sub-photolithographic groundrule structures whileavoiding “pattern-mismatch.”

The description of the embodiments of the present invention is givenabove for the understanding of the present invention. It will beunderstood that the invention is not limited to the particularembodiments described herein, but is capable of various modifications,rearrangements and substitutions as will now become apparent to thoseskilled in the art without departing from the scope of the invention.

For example, while the embodiments of the present invention formnano-fins from uppermost the single-crystal layer of an SOI substrate,the nano-fins may be formed from any semiconductor material, examples ofwhich include but are not limited to doped and undoped polysilicon,silicon-germanium and germanium, each formed on a dielectric layer (suchas silicon dioxide or silicon nitride) which in turn may be formed on asupporting substrate. Therefore it is intended that the following claimscover all such modifications and changes as fall within the true spiritand scope of the invention.

1. A structure, comprising: an array of nano-fins, each nano-fincomprising an elongated block of semiconductor material extendingaxially along a first direction, said nano-fins arranged in groups of atleast two nano-fins each, wherein ends of nano-fins of each adjacentgroup of nano-fins are staggered with respect to each other on both afirst and a second side of said array; wherein nano-fins of each groupof nano-fins are electrically connected to a common contact that isspecific to each group of nano-fins such that said common contactscomprise a first common contact on said first side of said array and asecond common contact on said second side of said array; and whereineach group of nano-fins has at least two gates that electrically controlthe conductance of nano-fins of said each group of nano-fins.
 2. Thestructure of claim 1, further including: a channel region in eachnano-fin between adjacent gates of said at least two gates; and arespective source region and a respective drain region in each nano-fin,said respective source and drain regions separated by a respectivechannel region.
 3. The structure of claim 1, wherein for each group ofnano-fins, at least one gate of said at least two gates is a controlgate adjacent to an outermost nano-fin of said each group of nano-finsand at least one gate of said at least two gates is a floating gatebetween adjacent nano-fins of said each group of nano-fins and whereinsaid control gate is tied to a voltage source and said at least onefloating gate is electrically floating.
 4. The structure of claim 1,further including, for each group of nano-fins, a gate dielectricbetween each nano-fin and gates of said at least two gates associatedwith each said group of nano-fins.
 5. The structure of claim 1, furtherincluding at least one memory element electrically connected to at leastone of said nano-fins of said array of nano-fins.
 6. The structure ofclaim 5, wherein said at least one memory element is selected from thegroup consisting of anti-fuses, DRAM cells, phase-change memory cells,solid-electrolyte memory cells, ferro-electric memory cells,magneto-resistive random access memory cells, oxide based resistivememory cells and organic-based resistive memory cells.
 7. The structureof claim 1, wherein a pitch of said nano-fins of said array of nano-finsin a second direction perpendicular to said first direction is less thana smallest pitch lithographically definable by a photolithographicsystem used to define each said at least two gates.
 8. The structure ofclaim 1, wherein a width of said nano-fins of said array of nano-fins ina second direction perpendicular to said first direction is less thanabout 50 nm.
 9. The structure of claim 3, wherein a width, in a seconddirection, of said floating gates is less than about 50 nm and a width,in said second direction, of said control gates is equal to or greaterthan about 180 nm, said second direction perpendicular to said firstdirection.
 10. A structure, comprising: an array of nano-fins arrangedin alternating first and second sets of two or more nano-fins, eachnano-fin of said first sets of two or more nano-fins comprising anelongated block of semiconductor material extending axially along afirst direction, and each nano-fin of said second sets of nano-finscomprising an elongated block of said semiconductor material extendingaxially along said first direction; on a first side of said array ofnano-fins, first ends of nano-fins of said first sets of nano-finsextending past first ends of nano-fins of said second sets of nano-fins;on a second side of said array of nano-fins, second ends of nano-fins ofsaid second sets of nano-fins extending past second ends of nano-fins ofsaid first sets nano-fins; a first set of electrically conductivecontrol gates on said first side of said array of nano-fins, eachcontrol gate of said first set of control gates located between adjacentsets of nano-fins of said first sets of nano-fins and located adjacentto a respective set of said second sets of nano- fins, said respectiveset of nano-fins disposed between said adjacent sets of said first setsof nano-fins; and a second set of electrically conductive control gateson said second side of said array of nano-fins, each control gate ofsaid second set of control gates located between adjacent sets ofnano-fins of said second sets of nano-fins and located adjacent to arespective set of said first sets of nano-fins, said respective set ofnano-fins disposed between said adjacent sets of said second sets ofnano-fins.
 11. The structure of claim 10, wherein control gates of saidfirst sets of control gates are aligned to each other in a seconddirection and control gates of said second sets of control gates arealigned to each other in said second direction, said second directionperpendicular to said first direction.
 12. The structure of claim 10,wherein control gates of said first set of control gates do not extendpast said first ends of nano-fins of said first sets of nano-fins andcontrol gates of said second set of control gates do not extend pastsaid second ends of nano-fins of said second sets of nano-fins.
 13. Thestructure of claim 10, wherein said first ends of nano-fins of saidfirst sets of nano-fins extend past said first set of control gates andsaid second ends of nano-fins of said second sets of nano-fins extendpast said second set of control gates.
 14. The structure of claim 10,further including: a first set of floating gates, each floating gate ofsaid first set of floating gates positioned between different adjacentcontrol gates of said first set of control gates and between differentadjacent nano-fins of each set of said first sets of nano-fins; and asecond set of floating gates, each floating gate of said second set offloating gates positioned between different adjacent control gates ofsaid second set of control gates and between different adjacentnano-fins of each set of said second sets of nano-fins.
 15. Thestructure of claim 14, wherein there is a floating gate of said firstset of floating gates between adjacent pairs of nano-fins of every firstset of nano-fins and there is a floating gate of said second set offloating gates between adjacent pairs of nano-fins of every second setof nano-fins.
 16. The structure of claim 15, further including:corresponding dielectric layers in direct physical contact with andbetween every nano-fin of said first sets of nano-fins and correspondingadjacent gates of said first set of control gates; correspondingdielectric layers in direct physical contact with and between everynano-fin of said second sets of nano-fins and corresponding adjacentgates of said second set of control gates; corresponding dielectriclayers in direct physical contact with and between every nano-fin ofsaid first sets of nano-fins and corresponding adjacent floating gatesof said first set of floating gates; and corresponding dielectric layersin direct physical contact with and between every nano-fin of saidsecond sets of nano-fins and corresponding adjacent floating gates ofsaid second set of floating gates.
 17. The structure of claim 16,further including: a channel region in each nano-fin of said first setsof nano-fins, said channel region between either a control gate of saidfirst set of control gates and a floating gate of said first set offloating gates or between two adjacent floating gates of said first setof floating gates; a channel region in each nano-fin of said second setsof nano-fins, said channel region between either a control gate of saidsecond set of control gates and a floating gate of said second set offloating gates or between two adjacent floating gates of said second setof floating gates; and a respective source region and a respective drainregion in each nano-fin, said respective source and drain regionsseparated by a respective channel region.
 18. The structure of claim 10,further including: a first set of contacts on said first side of saidarray, each contact of said first set of contacts in physical andelectrical contact with all first ends of nano-fins of a respective setof nano-fins of said first sets of nano-fins; and a second set ofcontacts on said second side of said array, each contact of said secondset of contacts in physical and electrical contact with all second endsof nano-fins of a respective set of nano-fins of said second sets ofnano-fins.
 19. The structure of claim 10, wherein pitches of allnano-fins of all first and second sets of nano-fins in a seconddirection are less than a smallest pitch lithographically definable by aphotolithographic system used to define said first and second sets ofgates, said second direction perpendicular to said first direction. 20.A memory device, comprising: a first set of nano-fins, each nano-fin ofsaid first set of nano-fins comprising an elongated block ofsemiconductor material extending axially along a first direction; asecond set of nano-fins, each nano-fin of said second set of nano-finscomprising an elongated block of said semiconductor material extendingaxially along said first direction and adjacent to said first set ofnano-fins; first ends of each nano-fin of said first set of nano-finsextending past first ends of each nano-fins of said second set ofnano-fins in said first direction and second ends of each nano-fin ofsaid second set of nano-fins extending past second ends of each nano-finof said first set of nano-fins in said first direction; a first gateadjacent to a first side and proximate to said first ends of nano-finsof said first set of nano-fins; a second gate adjacent to a second sideand proximate to said first ends of nano-fins of said first set ofnano-fins and adjacent to said first ends of said second set ofnano-fins; a third gate adjacent to a first side and proximate to saidsecond ends of nano-fins of said second set of nano-fins and adjacent tosaid second ends of said first set of nano-fins; a fourth gate adjacentto a second side and proximate to said second ends of nano-fins of saidsecond set of nano-fins; a first electrical contact to said first endsof nano-fins of said first set of nano-fins and a second electricalcontact to said second ends of nano-fins of said second set ofnano-fins; a set of electrically conductive wires extending in a seconddirection perpendicular to said first direction, each wire of said setof wires crossing over nano-fins of said first and second sets ofnano-fins; and memory elements electrically connected between wires ofsaid set of electrically conductive wires and nano-fins of said firstand second sets of nano-fins proximate to where said wires of said setof electrically conductive wires cross-over said nano-fin of said firstand second sets of nano-fins.
 21. The memory device of claim 20, whereinsaid set of electrically conductive wires comprises a third set ofnano-fins, each nano-fin of said third set of nano-fins comprising anelongated block of semiconductor material extending axially along saidsecond direction, and a fourth set of nano-fins, each nano-fin of saidfourth set of nano-fins comprising an elongated block of semiconductormaterial extending axially along said second direction and adjacent tosaid third set of nano-fins; wherein first ends of each nano-fin of saidthird set of nano-fins extend past first ends of each nano-fins of saidfourth set of nano-fins in said second direction and second ends of eachnano-fin of said fourth set of nano-fins extend past second ends of eachnano-fin of said third set of nano-fins in said second direction; andfurther including: a fifth gate adjacent to a first side and proximateto said first ends of nano-fins of said third set of nano-fins; a sixthgate adjacent to a second side and proximate to said first ends ofnano-fins of said third set of nano-fins and adjacent to said first endsof said fourth set of nano-fins; a seventh gate adjacent to a first sideand proximate to said second ends of nano-fins of said fourth set ofnano-fins and adjacent to said second ends of said third set ofnano-fins; an eighth gate adjacent to a second side and proximate tosaid second ends of nano-fins of said fourth set of nano-fins; a thirdelectrical contact to said first ends of nano-fins of said third set ofnano-fins; and a fourth electrical contact to said second ends ofnano-fins of said fourth set of nano-fins.
 22. The memory device ofclaim 21, wherein said first, second, third and fourth sets of nano-finscomprise single-crystal silicon.
 23. The memory device of claim 21,further including: a first multiplexer connected to said first andsecond contacts; and a second multiplexer connected to said third andfourth contacts.
 24. The memory device of claim 20, further including: amultiple voltage power supply coupled to said first, second, third andfourth gates; and either (1) a wordline decoder and driver coupled tosaid first and second sets of nano-fins, and bitline address decodersand sense amplifiers coupled to said set of wires or (2) a wordlinedecoder and driver coupled to said set of wires and bitline addressdecoders and sense amplifiers coupled to said first and second sets ofnano-fins.
 25. The memory device of claim 20, wherein pitches of allnano-fins of all said first and second sets of nano-fins in said seconddirection are less than a smallest dimension lithographically definableby a photolithographic system used to define said first, second, thirdand fourth gates.
 26. The memory device of claim 20, wherein said memoryelements are selected from the group consisting of anti-fuses, DRAMcells, phase-change memory cells, solid-electrolyte memory cells,ferro-electric memory cells, magneto-resistive random access memorycells, oxide based resistive memory cells and organic-based resistivememory cells.